Well screening device



July 30, 1963 M. K. MILLER ETAL WELL SCREENING DEVICE :5 Sheets-Sheet 1 Filed Jan. 23, 1961 132/ y z.. Afa/141.5@

July 30, 1953 M. K. MILLER ETAL 3,099,318

WELL SCREENING DEVICE Filed Jan. 23, 1961 3 Sheets-Sheet 2 U x' Q4 50 D] I l F7/CG. 6. j@ A u' u i 34 ,drivel/EK July 30, 1963 M. K. MILLER ETAL WELL SCREENING DEVICE 3 Sheets-Sheet 3 Filed Jan. 23, 1961 gun United States Patent O 3,099,318 WELL SCREENING DEVICE Montgomery K. Miller, Pasadena, Calif. (2404 W. 7th St., Los Angeles 57, Calin), and William L. Kunller, 523 W. 6th Ave., Los Angeles 14, Calif.

Filed lian. 23, 1961, Ser. No. 84,387 18 Claims. (Cl. 166 227) rThis application is a continuation-in-part of the copending applications of Montgomery K. Miller and William L. Kumler, Serial No. 637,687, tiled February 1, 1957, and Serial No. 689,002, led October 8, 1957, now Patent Numbers 2,981,332 and 2,981,333, respectively.

This invention relates -to 'the introduction of well fluids such as oil and water from a formation into a well, while preventing accumulation of particles of earth and sand in the well. The invention is particularly concerned with procedure for screening earth and sand particles against introduction into a well with the well huid, and `apparatus for this purpose.

yIt is known to mount filter elements on tubes or perforated liners which are inserted in oil wells. Frequently, however, a condition of running sands or cave-ins is encountered in a well, which causes the liners to stick, and also causes the introduction of sand and .other particles particularly into the annulus between the liner and the wall of the bore, and also into the oil Well string. 'Ihe main object of this invention is to provide a screening element around a tube or perforated liner so that it iills the vannulus between the wall of the Well .and the liner to prevent the introduction or the accumulation in said annulus of earth and sand which would block oli the liner and cause the difficulties previously defined, but which would be porous to permit the movement of oil through the screen and into the liner and up the tubing of the oil well.

The invention is directed to the use of an expansible screening element which surrounds the ltube or liner and has .an outside diameter which permits the introduction of the tube through the casing and into the open portion of the hole, and when the 'tube is in position said element can be permitted to expand to substantially till the annulus. A constricting element is positioned about the screening element or screen to hold it in compression. When the liner is placed in position in the well, the constricting element is released, so that the screen can expand due to its resiliency. Devices of this :type have been disclosed in the `above copending applications.

However, in some instances the screening elements of the devices of the above copending applications, although having good resilience, may not have the desired screening properties. That is, screening properties may be sacrificed in favor of greater resilience. On the other hand, some good screening materials have insufficient resilience for .application in the devices of the above copending applica-tions.

According to the instant invention, we can employ foraminous or porous screening components having good screening properties but relatively inferior resilience characteristics, and foraminous or porous screening components having good resilience but relatively inferior screening properties. Thus, we take advantage of the superior properties with respect to screening .and resilience of both types of components, while minimizing the eifect ice of the inferior resilience and screening properties, respectively, of said components, by combining these components in a screening element, for example, of the general type described in the above :copending applications, to obtain an improved screen.

The invention will be more clearly understood by reference to the accompanying drawings wherein:

FIG. 1 is an elevational view, partly in section, of one form of the invention device, located in position in a well bore;

FIG. 2 is a horizontal section .taken on line 2 2 of FIG. l;

FIG. 3 is a view similar to FIG. 1, showing the screening element in expanded position adjacent the wall of the bore;

FIG. 4 is `a horizontal section taken on line 4 4 of FIG. 3;

FIG. 5 shows a modification of the `screening element `and the constricting element of FIG. 1;

FIG. 6 is a view similar -fto FIG. 1, showing a mechanical form of constricting means for our device;

FIG. 7 is a horizontal section taken on line 7 7 of FIG. 6; and

FIG. 8 is a horizontal section taken on line 8 8 of FIG, 6.

FIG. 9 illustrates .another form of screening element which can be employed;

FIG. 10 illustrates still another form of screening element;

FIG. 11 illustrates use of still another modified form of screen element employed in connection with gun perforating; and

FIG. 12 is a view similar to FIG. 11 showing the screen in expanded position `adjacent the bore wall; and

FIG. 13 is `a section taken on line 13 13 of FIG. 12.

'Ii-hns, according to one embodiment of the invention, the screening clement can be formed of two components arranged as concentric tubes, the inner tube being in engagement with the outer periphery of the tubular liner, and the outer tube engaging the outer periphery of said inner tube. One of said components of the screening element preferably has substantially greater lresilience than the other component, and said other component preferably has substantially greater uid screening characteristics than the iirst component. In preferred practice, lthe inner tubular component of the screen is the component having superior resiliency, and the outer ltubular component is the one having superior screening properties.

The tenrn iiuid screening characteristics is intended to denote the ability to screen lout or deposit particles of sand, earth or foreign matter present in a Well fluid, without adversely affecting to any substantial extent the rate of flow of the fluid, or without substantially increasing resistance to lilow of such Ifiuid.

In such an arrangement, we can employ an inner tubular component composed of synthetic neoprene type rubber having high resiliency and satisfactory or inferior fluid screening properties, and we can employ as the outer tubular component, -a polymeric fluorocanbon woven or felted fibrous material such as polymeric tetrafluoroethylene fiber felt, marketed as` Armalon by the E. I. du Pont Company, or a woven polymeric tetrafluoroethylene, marketed as Teflon TFE by the Du Pont Company, these polymeric iiuorocarbon materials having improved fluid screening properties, and some resiliency. It will be understood, however, that these specific materials are mainly intended as illustrative, and we can employ other materials having suitable properties of good resiliency or goo-d fluid screening characteristics, as components in producing the multicomponent screening element lof the invention. For example a flexible polyurethane ether or ester foam can be used as the material of superior fluid screening properties.

The relative thickness of the inner and outer tubular components of the screening element can be varied as desired. In one preferred embodiment the inner tube wrapped about the liner and formed of highly resilient material can be substantially thicker than the outer tubular component having superior uid screening properties. Thus, the outer tubular component can be in the nature of a thin skin wrapped about the thick inner tubular component, so that in expanded condition with the screening element substantially filling the annulus, there wi-ll be a thin layer of material of superior fluid screening properties adjacent to and preferably directly in contact with, the wall of the well bore. Where the material having superior fluid screening ability is employed as a thin ilayer around the inner tubular component of high resiliency such screening material need have little or substantially no resiliency, since the much thicker inner resilient tubular component will expand sufficiently to carry the screening material -outwardly to a position adjacent to, or in contact with, the wall of the bore.

The inner and outer tubular components are connected at their engaging peripheries by any suitable means such that the outer tubular component is maintained attached to the inner tubular component after the screen element has been expanded by removal of the constricting means, but without forming a liquid barrier between the adjoining interfaces of these tubular components. This can be accomplished, for example, by spot glueing the tubular components at their contacting peripheral surfaces, or by heat sealing said components at their peripheral surfaces.

When the screen hereof is in the operative expanded position, lthe .outer tubular component of the screening element substantially lls the annulus between said component and the wall of the bore. In this position the outer periphery of said outer component can be adjacent the bore wall `or in direct contact with the bore wall. The screen functions primarily to hold back most of the loose sand about the periphery of the bore. Where the outer tubular component in the expanded position is not in direct contact with, but is closely adjacent the bore Wall, some sand will fall into the narrow annulus between the outer componnet and the bore wall, but when such narrow annulus has been lled with sand, the screen will prevent and hold back any further running sands.

Further, the outer tubular component of superior screening properties functions to trap and hold back any minor amount of sand particles which may enter the screening element together with the well fluid from the adjacent formation, while permitting uninterrupted flow of fluid through the outer tubular component toward the inner tubular compo-nent. For this purpose, the material from which the outer tubular component is formed is preferably one of relatively small pore size to enable entrapment of sand particles but without presenting any signicant resistance to ow of the well uid. The inner highly resilient tubular component of the screen, whose primary function is to expand and carry the 'outer tubular component into' contact with the bore wall, usually has a larger pore size than the material forming the outer tubular component, so as to assure free flow of well fluid from the router tubular component through the inner tubular component to the interior of the pipe liner, substantially without any resistance to such flow. Thus, substantially all of the sand particles which may enter the screening element with the well iluid are entrapped within the `outer tubular component. By the term material having good (or superior) screening properties is accordi-ngly meant a material which will entrap the sand particles of a well fluid without substantially increasing resistance of iiow of the uid through the material due to such sand entrapment.

If desired, the screening element can be designed so that the inner tubular component can be formed of the material of lgood huid screening properties but inferior resilience and the outer tubular component formed of a material of good resilience :but inferior iluid screening characteristics. In this modication, t-he outer resilient component is expanded to a position adjacent the bore wall and substantially fil-ling the annulus between the bore wall and said component. Some of .the sand particles entering the outer tubular compo-nent with fluid from the formation, may be entrapped within said outer component. However, all of the sand particles entering the outer resilient component with the well lluid may not be entrapped therein due to the relatively larger pore size of the resilient material of which the outer component may be formed, but substantially all remaining sand particles entering the inner tubular component with the well :duid will be deposited therein on passage of the fluid through the latter component.

ln use, the screening element of the invention is positioned about a tube or perforated liner, and the constricting element is positioned about the screening elenient to hold it in compression. As specific constricting elements which can be employed, we can wrap the screen element of the invention with an outside coating or sheath sufciently strong to compact it, which sheath can -then be removed by solution with a solvent or acid introduced into the annulus of the well to disintegrate said sheath and release the screen, or a mechanical :binding or constricting element may be used which can be released mechanically. For example, we can wrap the constricting ele-ment with cords vor strings which can be either cut or released by the introduction of a go-devil, which slides over the pipe on which the line-r is suspended, and thus releases the constricting elements to permit the screen to expand.

After the constricting element is placed in position about the screen to compress it, the too-l is passed through the well bore, generally through the casing therein, to the productio-n Zone. The constricting element is then released in the aforementioned manner, the resiliency of the screening element according to the invention permitting it to expand partially adjacent to or in contact with the 4face of the wall of the well bore. The screening element thus takes a position substantially against the well wall and is still under some compression while against the Wall. In this expanded position, the tubular screening element substantially completely iills the annulus between the wall of the well and Ithe liner on which the screen is mounted. The resiliency of the screening element maintains it in contact with said Wall during the producing operation, `and the differential pressure between ithe fluid passing into said element and the opposite force due to resiliency of the screen, is controlled so that it is insufiicient to compress and force the screen element away from the Well wall.

Thus, the screening element in its operative position closes off the annulus between the liner and well wall so that only a minor portion, if any, of sand and earth particles adjacent the wall fall into the annulus, and any such particles which do fall into the annulus, soon fill it. T-he :outer surface of the resilient tubular element functions to screen off the major portion of such particles While permitting the iluid to pass through to the liner. Any minor portion of sand particles which may be carried through the screening element are usually deposited within the screen, in the manner previously described, and are not carried into the liner.

Where the constricting means for the screening element is a sheath o-r is in the form of bands, of a metal such as zinc, magnesium, or aluminum, a minera-l acid such as hydrochloric acid can be used to -disintegrate the constricting member, a conventional inhibitor lbeing added to the acid to prevent corrosion of the steel well equipment. inhibited acids `of this type which can be used are those conventionally employed in acidizing wells. Where the constricting means is a plastic sheath or -bands made of plastic, e.g., a cellulosic .or a vinyl resin, an organic solvent which Wi-ll readily dissolve the plastic is employed. For example, in the case of cellulose acetate lbutyrate, the solvent may be za ketone such as acetone, .and 4in the case of polystyrene the solvent may be -an aromatic or chlorinated hydrocarbon. The plastic employed should be inert to oil and preferably also inert to acids.

We may also employ as the constricting means a sheath or bands composed of a material which will disintegrate by heat to release said means. Thus, we may employ certain alloys which will melt or disintegrate lby contact with hot water or hot oil, preferably bismuth alloys. In this case, the temperature required vfor melting the particular alloy employed should be higher than the temperature of that portion of the well through which the liner passes and in which it is positioned, so that the constricting member will not melt or disintegrate before it is positioned at the ydesired location in the well.

"ln the above cases, the screening element employed .should lbe constructed of a material which is inert to the means employed for releasing the constricting means. Thus, where an acid is employed for this purpose, the screening element should be inert thereto, and when an organic solvent is utilized for :disintegrating said means, the screen should be composed of a material inert thereto. Further, the screening element should be inert to oil. Also, said element should be resistant to the temperatures encountered in the well.

Alternatively the constricting element or elements may be released lby mechanical rather than chemical means. In this case, :for example, a metal sheath may be employed as -the constricting means, such sheath bein-g connected mechanically to la structure, which, `on actuation from the well sur-face, pulls the sheath up over the enclosed screening element, to per-mit the latter to expand substantially to the well bore in the manner previously described.

As an alternative type `of multicomponent screening element according to the invention, we can arrange the component having enhanced fluid screening properties and the component of high resiliency in the form of a plurality of alternate coaxially `arranged rings placed one above the other, each such ring being wrapped around the perforated liner. As a further alternative we can vform the screen element as a single tubular member formed of a plurality of segments each extending axially from one end to the `other of said `tubular screening element, and from the inner periphery of the tubular screening element radially outward to the outer periphery of the tubular screening elements. Alternate segments are composed of a material having substantially greater resilience than the adjacent alternate segments, and said adjacent alternate segments are composed of a material having substantially greater fluid screening characteristics than said first mentioned alternate segments.

In both of the above cases, a constricting member is placed about the screen to hold it under compression. When the constricting member is removed, the concentric rings or segments formed of the highly resilient material expand to a position closely adjacent to, or into engagement with, the bore wall, and simultaneously cause expansion of the rings or :segments formed of the material of good screening properties into a similar posi- -tion with respect lto the bore wall.

The screening element of the invention can also be composed of tw-o components, one having superior resilience and the other superior iluid screening properties, intimately interspersed in the form of a mixture throughout the screening element. In this embodiment, if desired, the component having superior fluid screening properties can be concentrated toward the outer periphery of the 4tubular screen, eg., in the form of a layer, and the `component of superior resiliency concentrated adjacent the interior of the screen.

Further, the components of our screen can be formed of resilient, expansible materials having multidirectional characteristics so that when the screening element expands laterally on removal of the constricting member, the screen element components expand in an axial as well as lateral direction, so that any holes formed in the screen components, eg., as by gun perforating the liner, will be substantially filled by expansion of the screen components in a direction at right angles to the lateral expansion thereof, thus retaining the fluid screening properties of the screen following formation of such holes. ln -this embodiment, it will, of course, be understood that the screen component having superior -iluid screening properties should be sufficiently resilient to possess such multidirectional `expansion characteristics.

Referring lto FIGS. 1 to 4 of the drawing, the tool comprises a liner 10 threadably connected at its upper end 12 to a collar 14 carried at the lower end of a pipe tting 15 which is jointed at its upper end to a liner pipe 16. Mounted above the collar 14 is a collar hanger indicated generally by the numeral 18, said collar hanger being of a conventional type, eg., as manufactured by S. R. Bowen & Co., Lane Wells, and other vendors. The liner hanger shown comprises an axially movable collar 22 mounted about liitting 15, the collar 22 being attached by means of a number of connectors 20 tto a series of `grippers 24. Said grippers when forced upward by a spring 26 mounted about fitting 15 between collars 14 and 22, pass over a conical portion 28 of pipe tting 15 and onto an enlarged cylindrical upper portion 30 of fitting 15 at the tool joint, causing said grippers to expand outwardly into gripping contact with the well casing 32. The structure of the liner hanger 18 forms no part of the instant invention.

The liner 10 is closed at its lower end 34 and has distributed about the major portion of its'surface a series of perforations 36 such as are conventional in slotted liners. A pair of spaced supporting rings 38 are mounted about the outer periphery of the liner 10 adjacent the upper and lower ends of the perforated portion of the liner. Between rings 38 is supported a screening element 40 covering the perforated portion of the liner. Screen 40 is formed of an inner tubular component 43 of high resiliency, for example, a neoprene rubber having fluid screening properties, :and lan outer tubular component 45 of superior screening properties and with some resiliency, e.g., a polymeric tetrafluoroethylene fiber felt, the inner and outer tubular components being relatively thick, such components being attached at their engaging peripheral surfaces by spot glueing or cementing such surfaces, eg., as illustrated at 47, employing ya suitable glue or plastic adhesive. Both of the tubular components 43 and 45 can 'be relatively thick, or one of such components can be thicker than the other. Preferably, the screening element 40 can lbe connected to the outer periphery of the liner 10 by a suitable cement `applied between their surfaces and preferably cove-ring only narrow peripheral portions near the top and bottom of the inner surface of the screening element land adjacent surface areas of the perforated liner, as indicated at 41, care being taken that `said cement does not cover the perforations 36. The glue or cement employed to adhesively connect the two tubular components of the screen 40, `and to cause its inner tubular component 43 to adhere to the liner should be one which will withstand temperatures up to say about 25'0" F., or more, is insoluble in water and crude oil, and which will be inert to the acid or solvent used to disintegrate the constricting element, e.g., sheath 42, where removal of said constricting element is to be accomplished by chemical means. Such .cement for bonding the screen 40 to the liner lo can be employed, together with the supporting rings 38, or the cement can be used alone without such rings, or the rings alone can be' used to support the :screening element `40 on the linery 10. Cements which can be used for this purpose are well known in the prior art, and include, for example, cements of the phenol-formaldehyde or ureaformaldehyde type, and the like.

The screen 4i) is compressed by a `cylindrical metal sheath 42, eg., of Zinc, magnesium, aluminum and the like, which ts tightly about the screen 40. It will be seen in FIG. 1 that the outside diameter of the constricting metal sheath 42 is yslightly less than the internal diameter of the well casing 32, permitting passage of :the liner through said casing.

When the tool is introduced through the casing 32 into the open portion of the well bore 44 adjacent the producing zone 46, the liner hanger I8 is actuated by means of a tool in a well known manner, t-o release the spring 2o and to cause the grippers of slips 24 to .contact the inner surface of the casing 32. The weight of the tool causes the grippers to tightly grip the inside wall of the casing 32, as seen in FIG. 3, to hold the liner l@ in position ybelow the casing. An acid solution such as inhibited hydrochloric acid usually employed in acidizing wells is then circulated down into the annulus 48 `between the metal sheath 42 and the bore 44, causing the metal sheath 42 tol disintegrate. Removal of sheath 42 results in partial expansion' of the lforaminous screening element 4u' into contact with the wall 44 of the well bore, as seen in FIG. 3, and filling the annulus 43.

Thus, for example, a screen having an initial thickness of about 2 under full compression, ymay expand say l, or half the original thickness, when it makes contact with the bore wall 44. The screen 4i) in the position shown in FIG. 3 has suicient remaining resiliency or outward force so that it is not pushed away from the wall by the pressure of the uid passing from the producing zone 416 into the screen 40.

During expansion of the resilient tubular component 43, the outer tubular screening componen-t `45 is urged outwardly to substantially iill the annulus 48, and may, and preferably does, snugly contact the wall of the bore, as illustrated in FIGS. 3 and 4. Should the outer component not quite engage the bore wall, loose sand will deposit in the remaining annular cavity Ibetween 45 and the bore wall, and compact around the screen. Engagement of the outer screen 40 with the bore wall during weil operation, minimizes furtherV introduction of sand and earth [particles into the annulus 4S lbetween the wall V44 of the well and liner 10. Although most of the sand is thus held at the wall of the bore, and is prevented from entering the outer tubular component 45 during flow of well iluids, any minor portions of sand entering screening component 45 wit-h the well fluid are essentially trapped therein, permitting iiow of well liuids containing little, if any, sand or solid particles, through the inner tubular component 43 and into the liner 19. The invention device is particularly designed t-o prevent running sands and caveins of the earth and sand `forming the walls of the bore.

li desired, the materials forming the components 43 and `45 of the screen can be reversed in position so that the inner tubular component is yformed of a material of superior screening ability and the outer tubular component is formed of a material of superior resilience but inierior uid screening properties. However, this is not the preferred embodiment.

The screening element 46 remains in the expanded position shown in FIG. 3 throughout the period of produc tion of the Well, or until after an extended period, the screening element may @become clogged .and require replacement. After release of the grippers 2.4 from the casing, in known manner, so that the liner hanger again assumes the position shown in FIG. l, the liner lo carrying the used screening element 40' can be lifted through the liner pipe lo to the surface of the well. Although in expande-d position, the screen can be pulled through the casing and removed from the well.

In FIG. 5 is shown a modiiied form of device of the invention, including a modified .form of screen element and a different type of constricting means for maintaining the screen 4t) in compression while the liner l0 is introduced through the casing to its position adjacent the producing zone, as described above. In this modification, the screen 40', is composed of an inner relatively thick tubular component 43' of high resiliency, and an outer tubular component 45 of superior fluid screen ability in the form of a thin layer or skin, c g. about 1/8 to about l in thickness in expanded condition, wrapped about and firmly attached to the inner resilient tubular component in a manner previously described, and the latter component is of relatively great thickness compared to the outer component 45. ln this embodiment, vouter component 45' need have minimum or substantially no resiliency, since it is expanded into a position adjacent the bore wall substantially solely by expansion of the inner resilient component, when the constricting means is removed. The outer component under these conditions is initially wrapped around the inner component when the latter is in an expanded position prior to compression of the unit by the constricting member, and when the constricting member is later released to cause expansion of the inner component, .the outer component assumes its initial expanded peripheral shape. This is a preferred form of screening element.

iFurth-er, in this modification, a series of spaced metal, eg., magnesium bands 50 are compacted about the outer periphery of the screen 49', to hold it under compression as in the case of the metal sheath 42, the outer diameter of the bands 5t) being somewhat less than the inside diameter of the casing 32, to permit wrapped liner 10 to pass freely through the casing. When the liner and screen 46' are in proper position in the well adjacent the producing zone, an inhibited hydrochloric acid solution of the type used `for acidizing wells is introduced into the annulus 48' between the wrapped' liner 10 and the well bore, causing the metal Ibands 59 to disintegrate and dissolve, thus permitting the screen 40 to expand to a position adjacent to or into engagement with the wall of the bore substantially to iill said annulus, as previously described.

In FIGS. 6 to 8 is shown still another modified form of constricting means for holding the screening element in compression about the liner 10, said constricting means being mechanically removable. Here a metal cylindrical sheath 52 holds the screen 4l) sufficiently compressed to permit passage of the liner 10 carrying said screen, down through the casing 32. Integrally connected to the upper end of the metal sheath 52 are -four lift straps 54, the straps being equally spaced circumferentially about said sheath. The straps 54 extend upward longitudinally of the tool and are integrally connected at their upper ends to a lift collar 56 disposed above tool joint 30, said collar 56 having a pair of diametrically opposed lugs 5S to which cables 6i) are attached by means of fasteners 62. It will be seen that the sheath 52 has an outer diameter less than the inside diameter of casing 32, and that lift straps S4 and collar 56 are spaced from the inner wall of the casing, permitting liner l0, its encased screen 40, and the straps 54 and collar 56 to pass down through the casing.

When the liner 10 and element 4t? thereon are placed in position below casing 32, cables 6i) are pulled upwardly, lifting collar 56 and straps 54, and in turn lifting the sheath 52; to cause it to slide upwardly over and out of contact with the screen 4i). This permits the screen to expand toward the wall of the bore, as described above.

Instead of employing a metal sheath 42 or metal bands Si?, we can use a plastic lbag or sheath, or we can employ plastic bands or cords to compress the screen element, said plastic material being, for exa-mple, polystyrene. In these instances the plastic sheath or bands can be dissolved or ydisintegrated by means of a suitable solvent such as an aromatic hydrocarbon. However, the solvent employed vfor this purpose should be one which does not attack the components of the screen. We can also use a sheath or lbands composed of bismuth or `bismuth alloys, and disintegrate such sheath or bands by the application of heat. Suitable alloys are, for example, the `folio-wing:

Where the well temperature is relatively low, we may use a lower melting bismuth alloy such as alloy A or B in constructing the above sheath or bands, and introduce hot water into the annulus between the wrapped liner and well bore, for melting the alloy to remove said sheath or bands and cause the screen iii to expand to the wall of the bore. When the well temperature is higher, we may use the higher melting alloys C, D or E, yand melt the alloy by circulating hot oil in said annulus to disintegrate the sheath or bands. It will thus be understood that `we can employ any suitable form of restraining means to maintain the screening element of the invention in compressed condition for passage through the Well bore or casing therein to the desired location in the well, and we can also utilize acids, solvents, heat or mechanical means to disintegrate or remove said restraining means.

While our device is especially designed for use in an uncased portion of a well, that is, in a Zone of the well in which the walls are formed by natural earth formations, as described above, our device also has application in a Well bore adjacent a production Zone wherein the well wall adjacent said zone has been lined with casing cemented in place and gun perforated in known manner to permit passage of fluids from the formation through the casing and into the well. For example, casing 32 may be extended down to the bottom of the well as seen in FIG. 1, and cemented in along production zone 46 by yapplication oi cement in an annulus between the outside of the casing and the well wall 44, and the casing and cement adjacent Zone 46 gun perforated. When the screening element 4l? is caused to expand by disintegration or removal of the sheath 42 or bands 5t), the screen will expand substantially into engagement with the casing, holding back sand and earth particles which pass with the well uids through the casing perforations, and preventing such particles from entering the annulus between the casing and the liner. v

In FIG. 9 is shown a modified form of our device. The tubular screen 7u is formed of a plurality of alternately positioned coaxial rings 72 of a material of superior screening properties, and a plurality of alternately positioned coaxial rings 74 of a screening material of high resiliency, the rings 72 being positioned between adjacent rings 74. The rings 72 and 74 may be of substantially the same radial and axial thickness, or one set of rings, say 74, can be thicker radially and/or axially than rings 72. Preferably, however, rings 72. and 74 have substantially the same radial thickness. Rings 'i2 and 74 are laminated or bonded together by any suitable cement or glue, and the inner periphery of the rings can be cemented or glued to the outer peripheral surface of the liner 10 by a suitable cement, as above described. A constricting sheath 75 similar to 42 can be iitted about the screen 7), holding the rings 72 and 74 under radial compression.

On removal of sheath 75 by a disintegrating liquid, such as acid, the resilient rings 74 expand radially, also radially expanding rings 72 of inferior resiliency and superior screening properties, so that the outer peripheral surfaces of essentially all the rings 72 and 74 are adjacent to or in contact with the bore wall.

in FIG. l0 is shown another form of the invention screen. The tubular screen is in the form of a series of axially extending segments, alternate Segments 82 being composed of material of superior screening ability and alternate adjacent segments S4 being composed of a material @of high resiliency and preferably some screening ability. The sides 86 of the segments 'are formed by radial vertical planes from the center of the tubular screen Si), and the ends 87 and 8S of the segments are portions, respectively, of the inner and iouter peripheral surfaces of screen 80. Although the radial thickness of segments 82 and 84 can vary, pneferably the lradial thickness of segments 82 and 84 is substantially the same. The sides 86 of adjacent segments 82 and 84 are bonded together by a suitable cement, and the inner peripheral surfaces S7 of such segments are bonded to the liner 10 by a suitable cement, as above described. The oonstnicting ele-ment, eg. in the form of a sheath 89 similar to sheath 42, holds the segments 82 a-nd 84 under radial compression. On removal of the constricting element 39, the resilient segments 84 expand radially, also causing expansion of the adjacent segments 82 of improved screening properties, all of the segments in this manner being urged into position adjacent to, or substantially into contact With, the Wall foi the well bore.

In the modiiication of FIGS. 11 to 13, a casing 110 is provided having connected to its lower end by means lof a collar 111 a tubular member 1112, said tubular member being closed ioff at its lower end as indicated at 114. Said tubular member 112 m-ay 'be integrally connected to the casing lor it may be a separate element connected to the casing in any suitable manner, such as by a conventional tool joint. In `any event, the tubular member 112 yforms a part of the casing. A cementing shoe 113 is ythreadably connected to the lower portion of the collar 1 11 by means lof external threads 115 on the collar.

A pair of spaced supporting nings 116 are mounted about the outer periphery of the tubular member 112 of the casing, adjacent the upper and lower ends of said tubular member 112. On member 112 and between rings 116 is supported la tubular tor ring-shaped screening element 118. The screen 118 is composed of an inner tubular fioraminous component 119 of a highly resilient material having multidirectional expansion characteristics, and an outer tubular foraminous component 121 of superior screening ability `and also having some resiliency and multidirectional `expansion characteristics. Thus, for example, the inner component of high resiliency may be a synthetic rubber such `as a butadiene-styrene or butadieneacrylonitrile rubber, or neoprene rubber, and the outer tubular component of good fluid screening ability can be ia plastic foam such as polyurethane ether, polyurethane ester or polyvinyl chloride foam. It will be noted, however, that both inner and outer tubular components 119 and 121 have resiliency and multidirectional expansion properties.

The screen components 119 and 121 `are bonded together at their adjacent peripheral surfaces, and the inner tubular component 1119 is `attached to 'the outer surface of pipe 112, by suitable cementing techniques, c g. spot cementing, as previously described.

Screen element 118 is compressed by a cylindrical metal sheath y122, eg., of Zinc, magnesium, aluminum and the like, which lits tightly about the screening element 118. It will be seen in FIG. 11 that the outside diameter of the constricting metal sheath 122 and the outside diameter of casing 110 yare each less than the internal diameter of the well bore 124, and also the shoe 113 has an outside diameter, slightly less than the internal diam- 1 l eter of the well bore, permitting passage oi this unit through and into the Well bore.

In employing the unit 125 including the casing 1115, pipe 1&12 `and the screening element 11S thereon, such unit is introduced into ythe well bore 124 and is positioned therein with the screen-ing element 1113 adjant the producng formation 126i. This formation may be located either adjacent to the bottom of the weil bore or it may be at any position along the well bore above the bottom thereof. When the casing with lthe screening yeiement 111% thereon is pnoperly positioned in the well bore, a cement plug 12S is formed between the casing 11G` and the wall of the bore, at a location just above the pipe 112 and the screening element 118 thereon. Such cementing is accomplishedl in conventional manner by passing cement through holes 130 in the lower end or casing 11i) just above the shoe 113, into the 'annulus between the casing 1110 and the Well bore, the cement plug being supported by the shoe 113. It will be seen that the cement plug 128 produces a water shut-oi substantially preventing drainage of Water from the `annulus above the plug into the annulus below between the screening element 113 and the well bore.

When the casing 1111 has been cen-sented in place as described above, the pipe 112 and the screening element 118 including components 119 and i121, can be gun perforated by conventional gun perforating procedure well known in the art, `forming the perorartions 132 in the pipe =112, `as shown in FIG. `12. Following the gun perorating procedure `acid solution such as inhibited hydrochloric acid, usually employed in acidizing wells, is then circulated through the bore 134105 the casing 110 and the bore 135 of pipe 112, through the holes 132 of the pipe 112 and vthe holes 136 shown in dotted lines and for-med in Ithe screening element 11S by the gun perforation procedune, and into the annulus 138 between the constricting element 122 `and the wall of the well bore. On Contact of the acid solution with the metal sheath 122, such metal sheath disintegrates. Removal of sheath 122 results in partial expansion of the screening element 118 to -a position closely adjacent to, or 4into contact with the wall 124 of the well bore, as seen in FIGS. l2 and 13, and lilling `annulus 138. This is accomplished by radial expansion of the resilient inner tubular component 1'19, which aids to radially expand fthe outer tubular component 121.

It will be particularly noted in FlGS. 12 and 13, that during radial expansion of the tubular components 119 and 121, the resilient materials forming lnhese components `also expand in a plurality of directions so that the material of member-s 119 and 121 adjacent the holes 136 formed therein by gun perforation, expands radially inwardly into such holes substantially to the center thereof, as indicated lby y'arrows 140, and essentially iilling such holes. Thus, it is noted that while the components 119 fand 121 of screen element 11S expand radially outward from the pipe 112 substantially to the wall 124 of the well bore, they also expand in `a direction at a 90 angle to such outward expansion, eg., in a direction axially along the casing 110 or well bore. However, it should be recognized that such expansion of the members 119 land 121 of element 118 into holes 136A may not completely ll these holes, and small irregular passages 142 at the center of lthese holes may be yformed when the walls of holes 136 are forced inwardly toward the center of lthe holes as shown in FlGS. l2 and 13. 'Ille element 11S in the position shown in FGS. 12 and 13 has suiiicient remaining resiliency or outward force so that it is not pushed away from lthe wall by the pressure of the liuid passing from the producing zone 126 into the screen.

The screening element 118 is maintained in' the expanded position shown in FIG. 13 throughout the period of production of the well, or until after an extended period, the screening element may become unduly clogged and require replacement.

Although l have specilically described the invention in terms of a two component screening element, the screening element of the invention may comprise three or more forarnincus components, at least one of which has superior resiliency :and at least one of which has superior fluid screening characteristics.

From the `foregoing, it is seen that the invention provides a novel apparatus, which permits removal of oil, water or other fluids from the production zone of a welll, and passage of such fluids into the well bore or perforated liner usually employed, without causing substantial amounts of sand and earth to be introduced into the annlulus between the bore and the liner, and thus interfering with the flow of tluids into the well. Our device has additional advantages, for example, the expansible screening element when partially expanded and compressed against the earth forming the wall of the bore, helps to support the wall against collapse while at the same time being insuiciently compressed against said Wall so that the well iluids can' pass into and through the screening element and into the liner. Further, our device reduces lthe `amount of earth particles introduced into the liner itself.

While we have described particular embodiments of our invention for the purpose of illustration, it should be understood `that various modications and adaptations thereof be made within the spirit of the invention :as set forth in the `appended claims.

We claim:

1. A device for insertion in a Well bore, which comprises a tube, an expansible screening element mounted on and surrounding said tube, said screening element being .formed of a plurality of foramin'ous components having liuid screening characteristics, one of said components having substantial resiliency, and `another of said components having greater fluid screening properties than said rst component, and 1a constricting means maintaining said screening element in compression, said constricting means being removable while said element is in said well bore, said element being expansible radially a relatively substantial amount on removal of said constricting means, and means securely maintaining said screening element on said tube after said constricting mean is removed.

2. A device as dened in claim l, wherein said one of said components is composed of neoprene and said another of said components is composed of a polymeric tluorocarbon.

3. A device for insertion in a well bore, which comprises a tube, an expansible tubular screening element mounted on 4and surrounding said tube, said screening element being formed of `a plurality of foraminous resilient components, one of said components having greater resiliency than another of said components, and said lanother of said components having superior fluid screening properties over said one of said components, and a constricting means maintaining said screening element in compression, said constricting means being removable while said element is in said well bore, said element being expansible radially a relatively substantial amount on removal of said constricting means, and rneans securely maintaining said screening element on said tube after said constricting means is removed.

4. A device as defined in claim 3, wherein said constricting means is in the form of a sheath surrounding said tubular screening element.

5. A device `for insertion in `a well bore which comprises a tubular liner, 1an expansible tubular screening element connected to said liner and snugly surrounding said liner, said screening element being formed of two foraminous components having fluid screening characteristics, one of said components having substantial resiliency `and the other of said components having substantially greater liuid screening characteristics than the first of said components, and a constricting means enga-ging said element under compression to thereby reduce the diameter of said element, said constricting means being removable while said element is in said well bore, said element being expandable radially a relatively substantial `amount on removal of said constricting means, to thereby substantially iill the annulus between said liner and the Wall of said bore.

6. A device `for insertion in a well bore which compri-ses a tubular liner, an expansible tubular `screening element connected to said liner and snugly surrounding said liner, said screening element being formed of two resilient lfo-rarninous components, one of said components having substantially greater resiliency than the other of said components and the other of said components having substantially greater fluid `screening characteristics than the iirst of said components, and a constricting means engaging said element under compression to thereby reduce the diameter of said element, said constricting means being removable while said element is in said well bore, said element being expandable radially :a relatively substantial amount on removal of said constricting means, to .thereby substantially ltill the annulus @between said liner and the wall of said bore.

7. A device as defined in claim 1, said components having multid-irectional expansion characteristics capable of expanding and closing holes of substantial size formed in said components.

8. A device as deiined in claim l, said constricting means being in the lform 4of a material disintegratable by a fluid which attacks said material.

9. A device as defined in claim 5, wherein said two components of said screening element are in the torm of two concentric ltubes, the inner concentric tube being in engagement with said tubular liner, and the |`outer concentric tube engaging the outer periphery of said .inner tube, said constricting means engaging Ithe periphery of said outer tube.

10. A device as defined in claim 9 wherein said inner tube has substantial resiliency and said outer tube has substantially greater `fluid screening characteristics than said inner tube, said inner tube having a substantially greater radial thickness than said outer tube, and said outer tube being in the form of a thin layer positioned around said inner tube.

A11. A device tor insertion in a well bore which comprises a tubular liner, an expansible tubular screening element connected to said liner and snugly surrounding said liner, said screening element being stormed of two resilient foraminous components, said two components of said screening element being in the form of two concentric tubes, the inner concentric tube being in engagement with said tubu a liner, and the outer concentric tube engaging the outer periphery of said inner tube, said inner tube having substantially greater resilience than said outer tube, and said outer tube having substantially greater uid screening characteristics than said inner tube, and a constricting means engaging the periphery of said outer tube and maintaining said element under compression to thereby reduce the diameter of said element, said constricting means being removable While said element is in said well bore, said element being expandable radially .a relatively substantial amount on removal of said constricting means, to thereby substantially till lthe annulus between said liner and the wall of said bore, and means maintaining said inner and outer concentric tubes connected at their 14 engaging peripheral surfaces when said constricting means is removed.

=12. A device as defined in claim 11, the material forming said forarninous outer tube being of substantially greater pore size than the material forming said inner tube.

13. A device as defined in claim 11, said components having multidi-rectional expansion characteristics cap-able of expanding and closing holes of substantial size rformed in said components.

14. A device as defined in claim 11, said constricting means being in the :form `of a material disintegratable by a iiuid which attacks said material.

15. A device as defined in claim 11, wherein said inner tube is composed of neoprene and said outer tube is composed of a polymeric tetraliuoroethylene.

`16. A device as defined in claim 6, wherein said two components of said screening element are in the form of contiguous rings 4disposed one above the other around said tubular liner, alternate rings being composed of a material having substantially greater resilience than the adjacent alternate rings,l and said .adjacent alternate rings being composed of a material 'having substantially greater iluid screening characteristics than said irst mentioned alternate rings.

17. A device las defined in claim 6, Iwherein said two components of said screening element are in the [form of a plurality of segments each extending axially from ione end to the other of :said tubular screening element, and from the inner periphery of the tubular screening element radially outward to the outer periphery o-f the tubular screening element, alternate segments being composed of a material having substantially greater resilien-ce than the adjacent alternate segments, and said adjacent alternate segments being composed of a material having substantially greater Iiiuid screening characteristics than said trst mentioned alternate segments.

18. A device for insertion in a well bore, which comprises a tube, an expansible screening element mounted on and surrounding said tube, said screening element being formed of a plurality of foraminous components having fluid screening characteristics, `one of said components having substantial resiliency, and another of said components having greater fluid screening properties than said first component, and a constricting means maintaining said screening element in compression, said constricting means being removable While said element is in said Well bore, said element being expansible radially a relatively substantial amount on removal of said constricting means.

References Cited in the file of this patent UNITED STATES PATENTS 1,229,437 Foster June 17, 1917 1,411,975 Matson Apr. 4, 1922 2,378,879 Zylstra .lune 19, 1945 2,796,939 Woodruff June 25, 1957 2,837,032 Horsting June 3, 1958 2,877,852 Bashara Mar. 17, 1959 2,981,332 M-iller et al. Apr. 25, 1961 2,981,333 Miller et al Apr. 25, 1961 FOREIGN PATENTS 9,854 Great Britain Apr. 23, 1903 of 1902 

1. A DEVICE FOR INSERTION IN A WALL BORE, WHICH COMPRISES A TUBE, AN EXPANSIBLE SCREENING ELEMENT MOUNTED ON AND SURROUNDING SAID TUBE, SAID SCREENING ELEMENT BEING FORMED OF A PLURALITY OF FORAMINOUS COMPONENTS HAVING FLUID SCREENING CHARACTERISTICS, ONE OF SAID COMPONENTS HAVING SUBSTANTIAL RESILIENTY, AND ANOTHER OF SAID COMPONENTS HAVING GREATER FLUID SCREENING PROPERTIES THAN SAID FIRST COMPONENT, AND A CONSTRICTING MEANS MAINTAINING SAID SCREENING ELEMENT IN COMPRESSION, SAID CONSTRICTING MEANS BEING REMOVABLE WHILE SAID ELEMENT IS IN SAID WELL BORE, SAID ELEMENT BEING EXPANSIBLE RADIALLY A RELATIVELY SUBSTANTIAL AMOUNT ON REMOVAL OF SAID CONSTRICTING MEANS, AND MEANS SECURELY MAINTAINING SAID SCREENING ELEMENT ON SAID TUBE AFTER SAID CONSTRICTING MEAN IS REMOVED. 